Simplify the expression. $(3y^{4}+6y^{3}-7y)(-6y^{3})$
Solution: First use the distributive property. $ 3 y^4 (-6 y^3) + 6 y^3 (-6 y^3) - 7 y (-6 y^3) $ Simplify. $-18y^{7}-36y^{6}+42y^{4}$